The metabolism of prostaglandins either results in their biological inactivation or in a conversion to another class of prostaglandins with somewhat different physiological properties. The objective of the proposed research is to study the enzymes cayalyzing the early steps in prostaglandin metabolism in the human placenta. The enzymes will be isolated and purified, their characteristics will be established and the mechanisms controlling their activity will be sought. BIBLIOGRAPHIC REFERENCES: Jarabak, J. and Braithwaite, S.: Kinetic Studies on a 15-Hydroxyprostaglandin Dehydrogenase from Human Placenta: The Reaction Mechanism and Mechanism of Action of Various Inhibitors. Arch. Biochem. Biophys. 177, 245 (1976). Westbrook, C., Lin, Y., and Jarabak, J.: NADP-Linked Prostaglandin B Dehydrogenase from Human Placenta. Fed. Proc. 36, 767 (1977).